MailPoet 3 plugin – forms

Hi,

I recently installed your MailPoet 3 plugin and would like to change the background color of the text fields in one of the subscription forms I created.

I changed the CSS but it doesn’t work. What I did is:

.mailpoet_textarea {
width: 300px;
border: 0px !important;
background-color: #ffffff !important;
}

Could you please tell me where I can make these changes?

Thank you in advance for your help.